1. Field of the Invention
The present invention relates to desoldering methods and apparatus, and particularly to such methods and apparatus by which a vacuum is applied for withdrawal of molten solder in an operator-controlled manner.
2. Background of the Invention
For removal of modular electronic components from a substrate, such as a printed circuit board, heat is supplied via a desoldering tool to melt the solder and vacuum is applied to then remove the molten solder; see, for example, U.S. Pat. Nos. 3,392,897 and 4,768,699.
Typically, vacuum desoldering devices for melting and removing solder from through-hole joints and surface mount lands have simple finger or foot-actuated switches with which the operator can start and stop the flow of desoldering vacuum. In all such devices, the time of vacuum flow is determined by the time during which the switch is actuated.
For complete removal of the solder, and for avoiding the formation of a re-sweat joint in through-hole applications, as well as for preventing clogging of the desoldering tip, heater and solder collection chamber, especially during repetitive production operations in which large amounts of solder are removed, the inventors have discovered that it is necessary that the vacuum flow be present at least for a minimum period of time. However, unskilled operators who try to work too quickly often do not actuate the vacuum flow (via the switch) for a sufficiently long period of time, leading to the above-mentioned problems.